1. Field of the Invention
The present invention is concerned with greatly improved topical medicaments which can penetrate the skin and transport an anti-inflammatory corticosteroid and/or an analgesic to enhance the effectiveness of such components. More particularly, it is concerned with such topical medicaments which include a penetrating solvent such as dimethylsulfoxide (DMSO) or an alcohol along with a corticosteroid and/or a counterirritant/analgesic, and, preferably, a rubefacient, one or more suspending agents (e.g., emulsifiers), and a carrier.
2. Description of the Prior Art
Corticosteroids such as the hydrocortisones and their various derivatives are known to be useful medicinal agents. For example, these substances can be applied topically for the purpose of treatment of dermatoses of various types. These materials are known to have anti-inflammatory, antipruritic and vasoconstrictive actions. The clinical efficacy of topical corticosteroids is dependent upon the extent of percutaneous absorption or penetration of the active drug through the skin. Factors influencing absorption include the agent used, the concentration of the drug, the vehicle used, and the anatomical site of application. Topically applied corticosteroid preparations are available in nonprescription form for the temporary relief of minor skin irritations, itching and rashes due to eczema, dermatitis, insect bites, poison ivy, poison oak, poison sumac, soaps, detergents, cosmetics, jewelry and itchy genital and anal areas.
In addition, corticosteroids have been prepared in injectable form for treatment of inflamed body parts such as knees or other joints. To give but one example, these preparations can be injected for the treatment of painful athletic injuries such as knee sprains and the like.
Dimethylsulfoxide (DMSO) is an extraordinary chemical in the form of a highly polar, stable, hygroscopic organic liquid with exceptional solvent properties. Its industrial applications are numerous and diverse, being used as a solvent for resins, fungicides, dyes, pigments etc., as a reactant for chemical synthesis, as an extractant, and as a reaction medium to accelerate rates of chemical combination.
DMSO has also been tested for use in certain types of topical preparations, e.g., see "Topical Pharmacology and Toxicology of Dimethyl Sulfoxide--Part I," Journal of the American Medical Association, Vol. 193, No. 10, p. 796, and literature cited therein.
Counterirritants are sometimes employed in topical medicaments for the symptomatic relief of pain. Counterirritants are agents that are applied locally to produce an inflammatory reaction with the object of affecting another site usually adjacent to or underlying the surface irritated. The intensity of response of the skin depends on not only the nature of the irritant employed, but also its concentration, the solvent in which it is dissolved, and the period of contact. A counterirritant drug is typically applied to the skin where pain is experienced. Pain is only as intense as it is perceived, and the perception of other sensations from the application of the counterirritant, such as massage and warmth, tend to crowd out perception of the pain. In addition, such products may produce an increase in the flow of blood to the muscles which, with concomitant waste disposal and other chemical changes, enhances recovery. Various types of counterirritants have been employed in the past, e.g., methyl salicylate, camphor, menthol, eugenol, eucalyptol and thymol.
Additional background patents and literature references in connection with the instant invention include:
U.S. Pat. No. 2,801,202--Compositions Containing Cortisone or Hydro-Cortisone with Phenylephrine PA1 U.S. Pat. No. 2,815,315--Analgesic and Antirheumatic Preparation PA1 U.S. Pat. No. 2,880,130--Anti-inflammatory Steroid Solutions PA1 U.S. Pat. No. 2,880,138--Anti-inflammatory Steroid Solutions PA1 U.S. Pat. No. 2,890,152--Topical Anti-inflammatory Compositions PA1 U.S. Pat. No. 3,019,162--Cinchophen-Hydrocortisone Topical Compositions PA1 U.S. Pat. No. 3,053,737--N-Acetyl-p-Aminophenol Anti-inflammatory Steroid Compositions PA1 U.S. Pat. No. 3,474,168--Prevention of Corticosteroid Side Effects PA1 U.S. Pat. No. 4,012,508--Topical Composition and Method PA1 "Rubs and Liniments," Facts and Comparisons, pp. 1653-1655 (1981) PA1 "Emulsifying and Suspending Agents," Pharmaceutical Necessities--Remingtons Pharmaceutical Science, Chapter 64, pp. 1244-1253 (1980) PA1 "Emulsions," Particle Phenomena and Coarse Dispersions--Remingtons Pharmaceutical Science PA1 "Hormones," Remingtons Pharmaceutical Science, 16th Ed., pp. 901-912 (1980) PA1 "Corticosteroids, Topical," Fact & Comparisons, pp. 1620-1628 (1981)